text:
Why aren't AMA certified radio-control club sites shown on aeronautical charts?
All this drone business wound up affecting us R/C fliers that fly only at local verified club sites. I wrote (told) the FAA that our local AMA R/C flying fields are constantly having "our" flight areas intruded on by full-scale aircraft that unknowingly fly over our field.
Why are permanent R/C airfields not shown on aeronautical charts?
In response to comments:

We are not near an airport.
We take note when overflown by 2500' or less
Drones with FPV can easily stay under 400' AGL as suggested by the FAA but they will very likely not be aware of the location of manned aircraft
Other RC aircraft have no way of knowing where the 400' limit is and can easily go much higher, and manned aircraft would not be aware of this

Are you near an airfield? Technically R/C flying is not restricted airspace, so it is very much the other way around to "full scale" pilots. How high are you flying that you are irritated by aircraft overflying your field?

What makes the flying areas "yours"? Rather than airspace available to all flying craft, subject to the same regulations?

Airspace in the US is controlled by 14 CFR Part 71 and by incorporation FAA Order 7400.11A. R/C flying fields are not, as far as I can tell, mentioned in the rules so there is no reason to put them on the charts.

Because R/C should not be flying high enough to interfere with actual air traffic!

Like @acpilot says, 400' is safe. Any higher is not. §91.119   Minimum safe altitudes: General. (c) Over other than congested areas. An altitude of 500 feet above the surface, except over open water or sparsely populated areas. In those cases, the aircraft may not be operated closer than 500 feet to any person, vessel, vehicle, or structure.

Model aircraft flying areas may be registered with a group such as AMA but there is no requirement to register these areas with the FAA. The current FAA rules expect RC pilots to stay out of airspace in use by manned aircraft, or give way to manned aircraft at all times.
It would require a lot of extra work for the FAA to register every AMA field and mark them all on charts or to enforce restricted areas around them. Also, model aircraft are not limited to AMA fields. This seems to be a reasonable compromise: the FAA lets you use the airspace as long as coordinate with nearby airports and avoid all manned aircraft.
The FAA has provided guidelines for model aircraft flying an an Advisory Circular (AC) as of January 2016:

Model aircraft operators should follow best practices including limiting operations to 400 feet above ground level (AGL).
The aircraft operates in a manner that does not interfere with, and gives way to, any manned aircraft

If you stay under 400 feet as the FAA suggests, you will not be interfering with manned aircraft, which should not fly any lower than 500 feet.
If you choose to fly above 400 feet, it is your responsibility to avoid manned aircraft. You can see them but they probably can't see your model aircraft. Stay aware of your surroundings, use a spotter if you have to.
Remember that the airspace belongs to manned aircraft, and you are only allowed to use it if you don't interfere with them.
See related question: Where is RC aircraft flying allowed in the US?


text:
Who has final authority over Air Force One?
U.S. FAA FAR 91.3 ("Responsibility and authority of the pilot in command") says that:

The pilot in command of an aircraft is directly responsible for, and
  is the final authority as to, the operation of that aircraft.

When an aircraft is operating as Air Force One, it would normally be flown by the designated high ranking USAF Officer, as a military flight.
Is the President, as Commander in Chief of the armed forces, able to over-ride the authority of the pilot?
For example, if one of the current Boeing VC-25's engines flames out and the captain announces that he has made the decision to take an option/ turn back - can the President override this decision and force him/her to continue the flight?

Military pilots are not subject to FARs.

Last time a president pressed a pilot to do what he thought was a bad idea was also the last time he was able to misuse his immense power.

I suppose in theory the president could fly his own plane. I never heard of a president doing so, but I have heard of two kings doing so.

@Joshua George W. Bush did it during a carrier landing on the USS Abraham Lincoln on May 2, 2003 while he was in office. He didn't land, but he did have the controls at some point in the flight.

@RonBeyer, operating the flight controls is not the same thing as being the pilot in command.

The pilot in command has final authority over Air Force One
Air Force Instruction 11-202, Volume 3 says the following in Chapter 1, part 1.1.1 (as in, the very first thing in the document):

1.1.1. Pilot  in  Command  Authority. The Pilot in Command (PIC), regardless  of rank, is responsible for, and is the final authority for the operation of the aircraft.

Just for fun, let's compare it to the civilian version that you referenced, 14 CFR 91.3:

The pilot in command of an aircraft is directly responsible for, and is the final authority as to, the operation of that aircraft.

Wow! Basically identical except that the military version goes out of its way to mention that rank is irrelevant.

And if the POTUS is with any military personnel, there is granted to be someone on board that outranks the pilot.

And whose authority is sufficient to make an active pilot in command a pilot out of command?

Rank is not absolute, the military has a concept of a situational or occupational rank. For example, guards have full authority to stop higher-ranked personnel, and turn them away if they do not show the necessary credentials to enter.

@rackandboneman - Your comment made me wonder enough that I made it a question

For comparison, is this still true for other US military aircraft?

@E.P. -- my understanding is yes -- the 11-202 is true for all USAF aircraft.  See here for an example of that instruction in action.

source: Stack Exchange

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sort: votes


text:
In VFR, what is the list for "why to look outside"?
It is obvious we must mainly look outside during VFR. But what is the (somewhat) complete list of why?

Short term:

keep wings flat (roll)
keep altitude (pitch)
collision avoidance (planes, birds, close obstacles)
keep heading (yaw)
close weather (avoiding close clouds)
what else?

Medium term:

check if we are at the expected place (points of reference)
collision avoidance (ground)
weather (distant conditions)
spot where to do an emergency landing
enjoy the view
what else?

Other :

it's the law (*1)

Edit:

(*1) from a comment from Jamiec

I'd say you've got the list pretty much covered...

All I would have added was "Because you're legally obliged to", but that's just a restating of some of your existing ones (cloud avoidance, collision avoidance)

Because that's where the accident is.

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text:
Drag vs Lift, Airplanes vs Sailboats
We know that sailplanes need big span, thin airfoil profile and twist (flying wings) to have a decent L/D ratio and fly more distance while a short take off distance STOL planes need (besides noisy and faulty engine) thick airfoils with flat surface and multielement wing (front slats and rear flaperons)
Do you think that sailboats are more related to drag reduction as sailplanes or to lift increase as STOL (as they are examples of both cruising and take off mode respectively)?
And in the case of sail vs keel?

As they have bouyancy, one might say that sailboats would favor drag reduction like sail planes.  STOL slats and flaps (see airliners) are only needed for takeoff and landing.  Airliners fold them up minimize drag in cruise.  See clipper and schooner to see how sailboats reduce drag.

Yes i forgot about the difference between aircraft take off and cruising, both for thrust requirements and lift and drag, and still this could apply in sailboats to low and high wind thrust scenarios or wind angle as upwind

Wind mills are another one.  The old style ones were more like STOL, but the newer ones incorporate aerodynamic (drag) improvements, enabling higher speeds in lighter winds.

Yes, these HAWT wind blades are high span and aspect ratio (that otherwise create noise and disrupts birds) that probably look more for rpm in low wind days. Wind turbines can be also VAWT and usually short span and aspect ratio as savonious that seek torque instead rpm and they can power any appliance (pumps, compressors, washing machines, drill, lathe,etc) with that torque without electricity

Since wind is free one might go for the max torque.  Gears can be added for PTO RPM.

One of the real keys here is Reynolds number.  At around 200,000 one can take advantage of lifting properties and sail even faster than the wind (iceboats).  In light airs,  it is probably best to hang out as much sail as possible, especially since boat speed (with water drag) will be less than wind speed.  But schooners usually sail circles around square riggers.

I think this is related to the boat speed related to it's weight and sail area and wind speed, so in low wind the drag is an issue while with strong wind the lift is an advantage.
The keel, daggerboard, rudder, leeboard and rest of hydrodynamic appendages create heel in the same direction of the sails, in the water the high pressure is leeward while in sails is in winward side and do the keel ballast try to counteract this combined heeling.
In a sailboat the drag is more predominant in the submerged appendages rather than sail drag
On the other hand the hydrodynamic lift is more important in upwind to avoid leeway (drifting) with the appendages "lateral resistance" and so for hydrodynamic appendages to increase lift in upwind and reduce drag we need aspect ratio rather than span while sails usually try to increase span to access to more wind power gradient and twist to reduce sail tip turbulence drag
In upwind the hydrodynamic appendages can be asymmetric airfoil to increase lift against leeway
On the other hand asymmetric flexible wingsails also create closer angles of attack in windward compared to common sails
This is a matter of the energy input, similar to sailplanes and engine planes so in low wind airfoil drag is more an issue and in high wind an airfoil with lift gives an advantage

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text:
How is taxi speed measured?
What is the maximum taxi speed and who defines it? has a lot of interesting thoughts and facts about what maximum taxi speed is admissible or practical. It brings me to this new question: how does a pilot know how fast he/she is going when on the ground, apart from just looking out the window?
Afaik most planes only have an airspeed indicator, which I suppose is not of much use while taxiing due to surface winds being in the same order of magnitude as ground speed. Also I wonder if an ASI has any usable accuracy near the bottom of its range. The same might be true of GPS speed indication.

Did some more research and found out GPS is much more accurate than I thought it was. http://www.ncbi.nlm.nih.gov/pubmed/15519597 and other sources find it better than 0.5 ms-1 most of the time. I guess that is better than what can be calculated from wheel speed, especially with big, fast wearing tyres.

On old 747-100/200 the ground speed was shown on the inertial navigation systems, and it was accurate at taxi speeds. These days I'm sure the glass cockpits can display the ground speed. It would certainly be accurate just as your car's GPS readout is accurate at low speeds. Looking out the window can be a surprisingly INACCURATE way of judging groundspeed, especially if a pilot has just transitioned from an aircraft  where they're close to the ground to one where their eye level is over 30 feet up.

Some aircraft have a "taxi speed indicator". Here's one I found on ebay for an Airbus:

Tops out at 20 knots, huh?  Good thing Southwest doesn't operate Airbuses -- they'd need a much higher top end than that!

These days in most aircraft, GPS units are standard. You can read your ground speed directly on the screen, which is really helpful when taxiing if you want some extra info about how fast you're going. Try to keep it under 20 kts!  This image is from my Garmin GNS-530W GPS unit in the air, but the display is the same on the ground. You can see the ground speed as GS in the bottom left corner (where it says 163 kts).

These days in most aircraft, GPS units are standard. <-- Citation Needed! (seriously, I can walk down the ramp and well over half the aircraft don't have a panel-mount GPS). They're becoming more common, certainly, but they're far from ubiquitous. Of course in 5 years time I'm pretty sure that statement will be correct :)

@voretaq7 fair enough, old ramp queens and J3 Cubs don't have em, but most anything newer than 1990 does. Don't think I'm ripping Cessna 180s either - but I meant what I said - "these days"

@Pugz, 1990? I don't think so. IIRC even some large jets only added it around 2000 when SA was disabled.

@JanHudec I guess I'm new school :-)

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text:
How is combustion directed in one direction in a jet engine?
The answer here explains how jet engines work. During the BOOM phase air expands, however, the expansion would be in both direction, say toward the turbine blades as well as towards the compressor blades. Why is it that the compressor blades are not affected by this, because the blow could actually cause the compressor blades to rotate in the reverse direction?

The shape of combustion chamber does the trick. It's expanding towards the turbine. Pressure is highest when the air leaves the last compressor disk. Fuel is added to keep pressure from dropping. The pressure it's just a bit lower but the amount and temperature of the air is much greater so the air can be used to turn turbine. To increase efficiency pressure drop is kept to minimum. If something wrong happens or throttle is advanced very fast compressor blades can be effected. The surge happens and flow direction reverses.
Look at the cutout picture of a real jet engine. It will be obvious. There are very simplified pictures of the jet engine that can make understanding confusing as they can be just wrong.

As answered by QuadmasterXLII on Physics SE:

The next question is, why do the products of the combustion go out
  through the turbine than back through the compressor? Consider: the
  compressor and turbine are approximately the same diameter, and
  turning at the same angular speed, but because the gas has expanded
  due to the combustion process, there is more volumetric flow through
  the turbine than through the compressor. Because of this, the blades
  of the turbine are angled more steeply to be at the same angle of
  attack to the local flow. This difference in angle acts as a lower
  "gear ratio." -- for a given lift, the steeply angled blade generates
  less axial force and more torque. That's why, for a given pressure in
  the combustion chamber, the turbine generates more torque and controls
  which way the whole assembly turns.

As I understand it, the air duct is wider in one direction, and/or rotor blades are arranged to offer less resistance to the air exiting in that direction, so most air is exiting in that direction. This applies sufficient torque on the shaft to rotate it and overcome the reverse torque on the other end of the shaft, where the airduct is more narrow and/or the blades are additionally "geared" to different ratio of torque-vs-pressure-drop.
These differences in air duct cross-section and blades angle of attack determine which end of the engine is which.

One way to look at this is that you have a certain geometry (e.g. dia of each section, the blade spacing etc.) and a certain set of boundary conditions (e.g. far away from the system the P & T must return to ambient + continuum changes in P / T / flow etc. + velocity at wall set to zero) and a combustion zone with a specific mass contribution per unit time.
The pressure distribution and local flow profile is what evolves when you solve the governing flow and conservation equations. With the additional constraints offered by gas laws, commpressibility equations, heat transfer equations etc.
Sure, with the right (wrong?) set of parameters you can indeed "expand in both directions".
My point is, perhaps the analogy or the easy to understand qualitative explanation only takes you so far. At some point the flow direction is what evolves from solving a particular geometry with a particular set of boundary conditions.


text:
Is an approval required to fly from the right seat?
I asked this as a comment in this question, but I thought it was worth asking properly to preserve it for future Aviation.SE generations.
Is there any sort of permission required to fly from the right seat of an aircraft? If I've done all of my training on the left side of a C172 is there anything stopping me from deciding one day to stick a passenger in there and fly with my right hand?
I acknowledge that for experienced pilots there shouldn't really be a safety risk in doing this, but many light aircraft displays/instrumentation are designed for the pilot being in the left seat.

Which country or regulations are you asking about?

Ideally Australia but would be interested in confirmation from other countries

In the US there is not, but I'm trying to find the regulations that say so. I flew right seat a few weeks ago. Its a little awkward from a controls and sight picture standpoint, but not unreasonable.

As Ron mentions in the comments here in the US it is not illegal by any specific regulations however...
Most GA aircraft (the smaller ones at least) only have a single set of instruments that reside in front of the left seat as you mention in the question. Lets say hypothetically you were flying right seat and something went wrong. Due to the angle of view you were not able to read an instrument and this lead to an accident. Lets say you lose your primary CDI/Glide Slope while flying an ILS approach and you need to use one on the far side of the cockpit. For some reason you are alone and in the right seat. If an accident did occur as a result of this you may be able to be held to

§91.13   Careless or reckless operation.
(a) Aircraft operations for
  the purpose of air navigation. No person may operate an aircraft in a
  careless or reckless manner so as to endanger the life or property of
  another.

Since the left seat was open and available for you. But other than that there is no regulation preventing such operation.
Ron  posted an excellent article in the comments below that has at least one quote worth mentioning

Aircraft insurance policies and flying club rules often specify that
  all flying is to be done from the left seat unless the pilot holds a
  current flight instructor certificate or has specific authorization.

While this is not an FAA regulation insurance companies or the rental/flight club you get your plane from may stipulate left seat only flying.

Good related read: http://aviationmentor.blogspot.com/2011/01/flying-right-seat.html


text:
Why is there a difference between aileron upwards and downwards deflection angles?
I have noticed that on airliners the ailerons have different angles if deflecting upwards than deflecting downwards. When deflected at the maximum angle maximum angle downwards is lower than when deflected upwards. I suppose that this is due to the fact that when the wing has to be deflected upwards and consequently the aileron moves downwards, the force required is lower as there is already lift being produced by the wing whereas the opposite would happen when deflecting the wing downwards and more power is required.
Is this assumption true or are there any other technical reasons behind this deflection angle difference?

You're correct that the ailerons are deflected differently when they are deflected up or down. This is done in order to counter the adverse yaw effect which occurs when ailerons are deployed. Consider the situation when the ailerons are deployed.

Image from aerospaceweb.org
One aileron is deflected downward while the other is deflected upward. One the side with the downward-deflected aileron, lift increases as the deflection effectively increases the camber of that portion of the wing. The opposite happens in the other side.
However, the drag is also affected by aileron deflection- both induced and profile drags. For same deflection, the profile drag increase is same in both the wings. However, the induced drag on both sides are not equal, with a larger amount the wing with the down aileron (as the lift is more and induced drag is proportional to the square of lift).
One way of overcoming this is to deflect the ailerons differentially, i.e. deflect the down aileron by a lesser amount than the up aileron. The following table shows the aileron deflection in a number of aircraft, which shows the differential aileron deflection ($\delta_{A}$ is the aileron deflection, in degrees).

Table from Aircraft Design: A Systems Engineering Approach by Mohammad Sadraey
This adverse yaw can also be prevented by the use of,

Frise ailerons
Use of spoilers (in the wing up aileron)
Cross coupled controls (rudder and ailerons).

There is another reason to use a differential aileron- to prevent tip stall at high angles of attack (stall speeds). The rolling couple on the aircraft is always the difference in lift between the two wings. At or near stalling speeds, it is better to reduce the lift in up-going aileron than increase it in down moving one and risk stalling it.

The last two lines list the same aircraft type, but some values are different. Is that a typo?

@JanHudec Looks like. Airbus gives the A340-600 (with MTOW 368t) aileron deflection as 25 degrees both up and down with spoilers aiding roll control. The previous listing maybe for another variant of A340 (with different MTOW), though I'm not sure which one.

You are right regarding the control forces. Differential ailerons is the easiest way to reduce aileron forces at high angle of attack.
The mechanism is as you suspect. Key here is the free-floating angle of the control surface. Since the wing creates lift, its hinged flap will be pushed up by that lift. The equation for the floating angle $\eta_f$ is
$$\eta_f = -\frac{c_{r0}+c_{r\alpha}\cdot\alpha}{c_{r\eta}}$$
with $c_{r\alpha}$ the hinge moment coefficient over angle of attack $\alpha$ and $c_{r\eta}$ the hinge moment coefficient over control deflection $\eta$. Both coefficients are normally negative and the absolute value of $c_{r\eta}$ is larger that that of $c_{r\alpha}$. The result is a trailing-edge-up floating position - the aerodynamic forces push the aileron trailing edge up.
This means that the up-moving aileron will do so with gusto while the down-moving side needs extra force to be moved. If you now change the gearing such that equal amounts of stick travel mean ever smaller deflection angles when the aileron moves trailing edge down, your leverage is improved. At the same time, the up-going aileron will help to push the control rods into the deflected state, so forces become smaller still, if both ailerons are connected with stiff pushrods.
This effect is greatest at high $\alpha$, as you can easily see from the equation above. It helps less in cruise when $\alpha$ is low, but then aileron movements will be small or even zero when a high-speed aileron takes over.
On modern airliners this direct link is missing, so they do not see the benefit in control force reduction. Nor do they need so since the ailerons are moved by hydraulic actuators. Here the main advantage is better stall resistance in slow flight. When the high lift devices are deployed, they induce extra suction on the outer wing and bring it close to stall. Without leading edge devices the outer wing would stall even before the full lift potential of the inner wing has been exhausted. Adding a large aileron deflection almost guarantees poor stall characteristics in the approach and landing configurations. This is the main reason for the reduced downward deflection in airliners.
Now to adverse yaw: Drag due to deflection is small and plays little part in the yawing moments unless one aileron has separated flow on its suction side (which means it is stalled). What really causes adverse yaw is the different tilt of the aerodynamic force vector on each wing. Remember that lift is acting perpendicularly to the local flow direction? The rolling wing sees a variation in angle of attack over wing span, with the angle of attack on the down-moving wing being increased from the rolling motion while the up-moving wing sees a reduced angle of attack. Consequently, the lift vector on the down-moving wing points forward while the one on the up-moving wing is slanted backwards. This is what causes adverse yaw.

I do agree fully with both previous answers, however we need to distinguish required relative defections for a bank order, from the maximum physical possible up and down deflections for the following reason:
Many modern aircrafts have a « droop » fonction which uses the ailerons to provide a flap effect when flaps are extended, in this case the droop function should not prevent  the ailerons roll function to work properly, thus the aileron maximum deflection, (with respect to the rigging aileron neutral position in the  clean configuration),might become larger for the downward aileron compared to the upward aileron.

How can you agree with both when they give conflicting answers?

I would say complementary

My reason to add an answer was nonsense like that the drag difference of the differential ailerons reduces adverse yaw. Unfortunately, one of the answers is full of this.


text:
How is the crew rest area on the A350 accessed?
As per this image of the A350, the crew rest areas have been placed on the top of the fuselage. How can this be possible and how would the crew get into the rear one since it seems that it is placed above first class?
I understand that the front one is accessible from the cockpit, but the second one seems to be straight on top the first/business class section. Is this actually practical?

There might be a passage between rest areas?

This isn't new. The 777 has been this way for many years and the 787 is designed this way, too. Single-deck wide-body aircraft have a rather large amount of space above the passenger cabin if the fuselage has a roughly circular cross-section.

It looks like your image came from this article, since they have the exact same one.
According to Boeing, this is the most practical place, and Airbus has finally decided they agree.

For the first time in Airbus aircraft –and after benchmarked[sic] Boeing´s configuration-, the A350 XWB’s crew rest compartments are in the aircraft crown.--All images and quotes from article linked above unless otherwise noted.

This image shows that the cabin crew's rest area is at the rear of the aircraft, while the flight crew's is up front. It also shows how they've shifted out of the basement and into the attic:

Image courteously, but unknowingly supplied by core77.com
Further down in that article they state why the crew rest areas are where they are:

The A350 XWB crew rests, located overhead in the crown area, have no impact on revenues space – whether cargo or passenger – and contribute to the efficiency of the A350 XWB cabin.

It also explains how you get there:

Entrances to these rest areas are located outside the passenger cabin, so they do not use up seat space. “This is the first time a crew rest area on an aircraft will have no revenue-generating impact,” A350 XWB Marketing Director Bausor said.

Unfortunately, I'm guessing that the crew rest areas do not actually have a skylight one might infer from this image:

I'm sure the day-shift crew would enjoy sleeping under the stars at night, though the night-shift crew probably wouldn't enjoy the bright sunlight while trying to sleep.

+1, but it might be good to explicitly mention that the second rest area is actually in the tail and not above the forward part of the passenger cabin as the picture in the question shows. This makes it more obvious how this doesn't waste revenue space in the passenger cabin.

@pcfreakxx yes, well, sadly, that's why they recommend hosting the image at imgur - in case the original goes offline. I'll see what I can do to remember what it was supposed to be and find a replacement.

@pcfreakxx actually, it's SE's new requirement that image links use HTTPS and the fact that the original image host doesn't have a properly configured certificate. I believe I've reinserted the original image, but the linked article (in the image credit) will take you to a nice article and several other images.

So what is in the other 'attic areas' that are not a rest area?

That's a great question, @KPK, and you should feel free to ask it!

https://aviation.stackexchange.com/questions/93784/other-than-the-rest-areas-for-the-crew-what-else-is-in-the-attic-of-an-airpl


text:
How can a 777ER fly from the 9000 ft runway at Bologna (LIPE)?
How can a 777ER be operated from the Bologna runway which is only 9000ft?
I recently took the Emirates flight and the aircraft was full. I suppose that it was close to max weight. According to wiki the required runway at max load is 10000ft so what is the trick behind this?

LIPE - OMDB is only around 4,500 KM (2,800 NM) according to Great Circle Mapper, which is nowhere close to the 773ER max range of 14,500 KM (7,830 NM), so one can make an educated guess that the aircraft wasn't at MTOW.

Was actually thinking about it. Just needed some confirmation. So probably they would reduce the fuel load?

@FabrizioMazzoni For sure.

Every airline flight is done with minimum fuel these days. Any  extra fuel costs money in additional fuel burned in order to carry the extra weight of fuel that is not needed to complete the flight.


text:
Why are some engine nacelles thicker than others?
Why are the engine pods on the Embraer 190 thicker, related to the overall diameter of the engine, than most of the other pods on other jets? Wouldn't this design add more drag and reduce efficiency?
Pictures added for reference.
Embraer 190:

Boeing 737:

Airbus A330

Well. I didn't manage to find proper images but I have flown on one yesterday and it was very clear whilst boarding that the pod was really thick compared to other aircraft.

Relative thickness. Will modify question.

Perspective might fool you here. It looks much thicker from further away and photographed with a long focal length, because it tapers towards the front. It also looks thicker with a relatively small fan diameter, just because it's larger in relation.

The nacelle contains a lot of equipment for controlling the engine. While this will certainly scale with the size of the engine, there is also some amount of minimum space needed for the components. The volume also increases faster than the surface area, so there is more room to spread things out. You will notice that the general trend in your pictures is relatively thinner nacelles as the engine diameter goes up:
E190 - CF34 - 57 in
B737 - CFM56 - 61 in
A330 - CF6 - 105 in
The difference between the CFM56 and CF34 isn't that great, but I think your image of the 737 isn't the best for comparison. If you look at an image more comparable to the CF34 picture you have, like this one, they appear much more similar.

authors: Илья Соболев САА плнприсаша


text:
Can any aircraft adjust the wing dihedral in flight?
Are there any aircraft that can mechanically modify the dihedral angle of the wings whilst in flight? Would this solution give any advantage?

Fabrizio, you call this a solution.  What problem are you trying to solve?

Every aircraft increases the dihedral angle with load factor.

@SkipMiller I think that his second question was about the existence of such a problem.

Birds do it, bees do it Even educated fleas do it ... so why don't airplanes?

The final sentence might be better worded as "is this a solution to anything?" or something equivalent but less awkward.

http://memory-alpha.wikia.com/wiki/Klingon_Bird-of-Prey

The flapping hinge of a helicopter rotor might be construed as permitting variable dihedral.

There was one, and it did it to increase directional stability at supersonic speed. I am talking of the North American XB-70, of course. There were three benefits to this configuration:

Improved directional stability. Without the effect of the folded-down wingtips, the XB-70 would had lost all directional stability upwards of Mach 2. The wingtips folded down to 64.5° anhedral (or is it -64.5° dihedral?) which effectively made them into ventral fins. This answer explains how a ventral fin is especially helpful at supersonic speed, because it works in the compressed air below the aircraft.
Less shifting of the aerodynamic center. Since the transition to supersonic flight will shift the aerodynamic center back, folding the wing tips down reduces lift in the aft section of the wing, thus reducing the aftward shift.
Better capture of the compressed lower wing flow for lift creation, which is called a waverider. This increases the pressure on the lower side of the wing at high supersonic speed and allows to fly with a reduced angle of attack, thus reducing drag.

XB-70 landing with wingtips straight (picture source)

XB-70 in flight with wingtips down (picture source)
The XB-70 is also one of only a few types where every aircraft ever built had different dihedral: AV-1, the first prototype, had 0° while AV-2, the second prototype, had 5° dihedral over the whole wing to improve yaw and roll stability. Only the dihedral of the outer panels could be adjusted in flight, however. According to this source (PDF!) they were the largest moveable aerodynamic device ever used on an airplane.
Other cases of variable dihedral were less intentional, though, and there was really no advantage to it:

Like on many Navy aircraft, the wings of the F-4 could be folded for stowage. If the mechanism was not locked, the wings would fold up. The F-4 was even powerful enough to be flyable this way. When only one side folded up, the F-4 would crash, however.

could you elaborate a bit more on how the folding of the wing tips increased directional stability exactly? I don't quite understand how it would help.

@ROIMaison: They folded down to 60° anhedral which effectively made them into ventral fins.

That makes sense, thanks!

It has been said that with a strong enough jet engine, even a brick could be made to fly. The F-4 required two.

@dotancohen: This is soooooo true! The aerodynamics of the F-4 were outright horrible.

@PeterKämpf - aerodynamics? F-4's don' need no steekeeng areodynamics! You just sit yerself down in that chair right there, strap a couple of big ol' J-79's across your back, and I assure you - aerodynamics will not matter. :-)

In general, any aircraft will have its dihedral modified in flight due to the aerodynamic loads, though it is more pronounced in case of aircraft having high aspect ratio and slender wings like the Boeing 787.

Image from stackexchange.com
The North American XB-70 had a wing tip which was foldable in flight, which helped trap the shock wave under the wing between the downturned wing tips, creating compression lift, and also improved directional stability at high speeds by adding more vertical surface to the aircraft and reducing the rearward shift of aerodynamic center.

"XB-70 final proposal" by NASA - NASA CR-115703, Volume 2, page 23.Transferred from en.wikipedia to Commons by TheDJ using CommonsHelper.. Licensed under Public Domain via Commons.

Ornithopters vary their dihedral all the time.

Ornithopter built by University of Toronto School of aerospace technologies; image from philschophoto.com

Hang-gliders are an obvious answer.  For over 30 years, all higher-performance hang-gliders have had a pull-cord to tighten/loosen the sail, variously called "variable billow" or "variable geometry".  A sail which billows more in the middle will naturally give you higher dihedral.  The tradeoff of course is higher drag, which is why it's controllable - pilots pull on VB/VG for best performance in glides, and let it off for tight manoeuvring (e.g thermalling) or slow flying (e.g. takeoff/landing).

Re "A sail which billows more in the middle will naturally give you higher dihedral." -- are you sure? Sail billow causes the trailing edge to rise as you trace from root to about halfway out to the wingtip, but then to descend again as you trace from about halfway out to the wingtip on out to the wingtip. Sort of a gull-shaped geometry, as far as the trailing edge is concerned. Viewing the wing from multiple different angles (with the sail loaded) we can see that this creates a dihedral geometry inboard and an anhedral geometry outboard.

As long as the taper ratio is not too extreme (i.e. as long as the wing area of the outboard anhedral portions is not too tiny), it seems reasonable that the anhedral geometry of the outboard portions should dominate over the dihedral geometry of the inboard portions, by virtue of the greater moment-arm of the outboard portions from the CG. Thinking specifically of, say, the roll torque generated during a sideslip-- is it dihedral-like (acting to raise the "upwind" wingtip) or anhedal-like (acting to raise the "downwind" wingtip)?

Some in-flight experiments I've conducted suggest that tightening the VG cord shifts the slip-roll coupling at any given airspeed to give a weaker dihedral effect or a stronger anhedral effect.

(Re-posted some of that to fix errors)

authors: Bob Jarvis - Слава Україні


text:
Can the "Flying Whales" cargo airship really hover to be able to lift freight on board?
The figure below shows a cargo airship called "Flying Whales LCA60T" able to carry 60 tons of freight. In order to take the useful load from one location, the dirigible has to discharge up to 60 tons of water.
I know that its 32 thrusters are fixed: they can not pivot, but they can modify the pitch angle of their blades in the interval [-pitch_max, pitch_max].
My question would be: How can this airship position itself along the longitudinal axis of a container, or group of containers, in order to lift them on board, if the wind blows perpendicular to the longitudinal axis of the containers and of the airship?
I know that the airship is designed to work in winds as high as 11 m/s.
Yes, LCA60T can orient itself with the nose in the wind while hovering but the containers could have a position that is perpendicular to the wind. Besides this, while hovering, the airship has to be able to face lateral winds of at least 3-4 m/s because it is designed to work in the north of Canada (and other unfriendly locations) where the wind blows continuously.
Another question: What would be the lateral drag coefficient of LCA60T? (If I know the lateral drag coefficient of the airship, I can calculate the power needed by this machine to keep zero lateral speed (to hover) in a lateral wind of a few meters per second.)
The drag coefficient of such an airship while moving forward can be between 0.023 and 0.045 according to a 1932 study
Some explanations: LCA60T has two groups of 6 thrusters whose main purpose is to push the airship forward. It also has 4 groups of 4 thrusters each, I guess for stabilizing the airship in pitch, especially while hovering. There is also a group of 4 thrusters placed above the nose of the airship for yaw control at low and zero speed.
All 32 motors are electrical and are powered by a group of 4 helicopter gas turbines that each turns an 1 MW electric generator. So, in total, the max power available for the 32 thrusters is 4 MW.

Flying Whales - An industrial project to revolutionize air cargo transport (Video posted on Jun 13, 2023).
Technical characteristics:

Length: 200 meters
Diameter: 50 meters
Volume of Helium: 180,000 cubic meters
Number of Helium bags: 14 nonpressurized helium cells
Useful load: 60,000 kilograms,
Cargo bay volume: 96 m by 8 m by 7 m high cargo bay
Speed: max 100 km/h, 80 km/h cruise speed
Range: 400 to 500 km around its base. Most of the time, the airship will fly no more than 100 km from its base. Each time (day) the airship will return to the base.
Hovering capabilities: LCA60T’s has a unique stationary hovering design for loading and unloading
Max altitude: 3000 m
Powerplant: Four Honeywell 1 MW turbo-generators
Efficiency of the 1 MW generator: 97%, Weight: 280 pounds, Power density: 8 kW/kg
The 1 MW generator can also be used as a motor
Number of thrusters: 32
First flight: the end of 2025 (most likely later). Serial production begins in 2027 at the earliest. Place of building the first airship: Laruscade (near Bordeaux), France.
Crew: 3, including a pilot and loadmaster
Daily operating cost: about $50,000

LCA60T delivering humanitarian aid.

LCA60T landing on its cradle.
Flying Whales reveals the design of LCA60T.
The two picture above show no ground crew orienting somehow, using cables, the airship while it hovers.
UPDATE:
Based on the lateral drag coefficient given by Peter Kämpf, I estimated the power needed to keep LCA60T hovering in a lateral wind of 5 m/s and no headwind. (The lateral cross section of 8400 m2 I estimated by using the top view image of the airship. I also took into account the surface of the rear fins.)

This is a view from above of the LCA60T. Length = 200 m, max diameter = 50 m.

Comments have been moved to chat; please do not continue the discussion here. Before posting a comment below this one, please review the purposes of comments. Comments that do not request clarification or suggest improvements usually belong as an answer, on [meta], or in [chat]. Comments continuing discussion may be removed.

The design shows a few features which let me suspect that this is more an artist impression than a proper design.

The tail surfaces are rather small for the size of the envelope.
The hull seems rather stubby, with a diameter/length ratio of 1:4. A more slender design is much easier to control and has less drag, albeit at the cost of lower structural efficiency. 1:6 would be more credible.
Arranging the propellers in line reduces their efficiency. I would understand counter-rotating pairs of two, but certainly not four in a row, each on their own mast.
With that stubby hull the cruise speed will be very close to the critical speed. I doubt that anyone really looked into this!

Now to your first question:

How can this airship position itself along the longitudinal axis of a container.

It cannot. The airship has to be aligned with the local wind direction. There are two rows of sideways-blowing propellers on the top of the ship which can give the ship a limited sideways speed. However, since the rear row is further away from the rear end than the forward row is from the forward end, the forward row of propellers can only run at full power when the airship is meant to yaw. Also, besides a side force their location will cause a rolling moment.
Given the low propeller efficiency resulting from their position near the hull and the power needed which you calculated for a wind speed of 5 m/s, I estimate that roundabout 1 MW of electric power will be needed to keep the ship steady at a lateral wind speed of  5 m/s - with a substantial roll angle so the sideways shift of the low center of gravity can counteract the rolling moment of the side thrusters.
At the beginning of the payload pick-up process, when the airship is well balanced, a stronger sideways breeze will let it pivot around the payload like a kite. Only when in the middle of ballast release will there be noticeable tension on the crane cables and still enough weight of the payload to function as an anchor. Once the container is lifted up, it has to swivel to align itself with the airship. Given a bit of free space, this can be accomplished easily, with a few persons helping to dampen the movement of the container by pulling on ropes hanging from the container.
What is less easy to control is compensation of sudden gusts. Even a ground crew of dozens of people was insufficient in the past to prevent the sideways movement of airships in gusts.

LZ 8 after being blown into the hangar by a gust (May 16, 1911). Image source.
Airships had to respect weather conditions much more than airplanes do today. Their inertia prohibits them from fast maneuvering, so gusty weather must be avoided. Also, since the release of water ballast has to be finely coordinated with lifting up the load, any such pick-up maneuver will take several minutes in which the airship needs to stay reasonably close to the cargo, which will have progressively less ground load as the dumping of ballast progresses. Some sideways motion of the cargo shortly before the airship is light enough to lift it off the ground must be taken into account.
and your second question is:

What would be the lateral drag coefficient of LCA60T?

I would use the value for a horizontal cylinder and mix a bit of a sphere into it. The cylinder has a drag coefficient of 1.17 and the sphere 0.47, so in total, given that the cyclinder is dominant, it should be a value between 1.0 and 1.1.

Thank you very much for such a comprehensive and helpful answer. Based on the lateral drag coefficient estimated by you, I added an update to my post in which I attempted to calculate the power needed to keep the airship fix above a location. (If there are mistakes I will correct them.)

@RobertWerner With your updated question I noted that there are corresponding lower propellers for creating a side force. I need to update the answer.

Peter Kämpf said: "There are two rows of sideways-blowing propellers each on the top and bottom of the ship". I am not sure I understand this statement. Yes, from the picture I posted (which is a view from above not from one side) it appears that this is the case but in fact the 16 propellers distributed in 4 groups have their shafts pointing in the vertical direction as in the case of a quadcopter. However, as the thrusters can not pivot, the airship has to develop some roll angle to move sideways. There are only four propellers on top on the dirigible close to its nose.

@RobertWerner I mistook the top view of the last picture as a side view. Sorry!

This is what I found just a few hours ago: "Flying Whales : 90 millions euros public money invested and still no airship prototype" (Radio France, 03/05/2024) (https://www.francetvinfo.fr/economie/industrie/enquete-flying-whales-90-millions-d-euros-d-argent-public-investis-et-toujours-aucun-prototype-de-dirigeable_6521282.html). It appears that, a similar project, CargoLifter CL-75 (https://www.youtube.com/watch?v=lralh-LwcJQ) worked, also, in that case, an anchored aerostat was used, so the drift of CL-75 due to wind was prevented by ground means.

@RobertWerner To expect a prototype after only 90 Million is a bit unrealistic. Cargolifter was almost 30 years ago, and back then the estimates for a certified design ran at 6 Billion Marks. Of course not by the Cargolifter people but by competent experts. I was there with them to examine the feasibility ...

So, Peter Kämpf, I understand that you was one of the experts who examined the feasibility of the CargoLifter CL-160 airship. 6 billion marks were then 3 billion euros. Even if a Flying Whales airship prototype required a sum of the order of 1 billion euro (and I understand that it would be unrealistic to built it for less), there would be no chance this airship will be built. This money are not available.

@RobertWerner Yes. A flying prototype will cost less, but full certification will be much more than that and be so expensive. And is required to earn revenue with the design. To break even, you will need a fleet of at least 100 such airships, operating successfully over decades. This again requires serious infrastructure on the ground.

@PeterKämpf I feel it's a shame to see so much of your brain power wasted on a Stupid Photoshop Image :/  This "project" is nothing more than a couple of cheap photoshop videos.

The project originated from ONF (the French National Forests Office) employees to improve the 4-ton capacity of helicopters carrying wooden logs from mountainous areas. The startup was created 12 years ago, funded by public and private funds from different countries, now targets multiple industries. Several fundraising campaigns have been successful but the project also gives rise to skepticism. Funding such projects is part of France history and has been revitalized under its current administration. At this time public investment in the project amounts to 90 millions euros.
A similar project in Belgium, FlyWin, was discontinued after testing a demonstrator.
The key need is the capability to load and unload while hovering, to allow operations on slopping ground. Horizontal stabilization is critical, as well as altitude keeping while transferring the load. A first test flight was initially planned for 2020, now delayed to 2028. According to this post:

Stabilization will be based on 32 propellers.

The team was testing them in a wind tunnel last Summer.

Our test also aims to evaluate the thrust generated by these propellers under high sideslip conditions. This data is essential for optimizing airship performance in challenging scenarios, ensuring safety and efficiency.

As long as the design is not complete, and the first flight not done, what can be said? We have seen here other highly speculative projects which are still not operational.
According to this article (in French), among the many problems to solve:

How to transfer 60 tons of freight to the ground and simultaneously load 60 tons of ballast? This problem is known since a long time and no solution has been found yet to keep the airship stable during this dual transfer.

The use of water ballast at freezing temperatures (Québec is part of the project). Tanks must be drained but also refilled while hovering.

The use of helium, subject to recent shortages and price variations. Filling the envelope could be as costly as several millions dollars, tightness is critical.

The navigation in windy conditions, which can slow or stop the aircraft.

The description as a "highly speculative project" seems extremely applicable here. Airships are anything but a new concept; what is new and so much better here to change the underlying economic and operational realities that have made them little but relics and an advertising oddity?  Until it's flying & making money without massive subsidies, my skepticism will remain.


text:
Why is the F-16 still in service?
Reading the Wikipedia page, I see that the F-16 began production in 1973. That seems pretty old to me. So I ask, why is the F-16 still in service in many countries around the world? Is it that a superior fighter has been not been designed yet, or are there other reasons?

The F-14 is actually the only US fighter from that era that's been totally retired, and even not that long ago.

@fooot isn't the Iranian air force still flying them?

@DeltaLima I think so. I guess by "totally retired" I should have added "by the US." Much older fighters are also still in use, just not in as many places anymore.

two words: Iron Eagle

The simplest answer to your question is that the F-16 has not yet been retired because, for its cost, there's nothing better being built in enough numbers to replace the nearly 4500 Falcons produced.
The F-16 was designed on the trailing edge of a surge in technological development by the U.S. military in the wake of Vietnam. The U.S. had fought that war with an air force primarily designed for a standoff engagement with the Soviet Union directly, thus emphasizing interceptor-style fighters targeting bombers at extreme range using missiles. Robert McNamara, U.S. SecDef for the Johnson and Nixon administrations, also emphasized a "one-size-fits-all" approach to aircraft design, requiring the USAF and Navy to collaborate on common aircraft designs that covered a multitude of mission profiles. This created the F-4, a fast but heavy plane that was a handful to fly, weaknesses that were exploited by pilots of technologically-inferior MiG-19 and MiG-21 aircraft in close combat engagements that the Phantom was ill-prepared to fight.
The lesson "dogfighting isn't dead" prompted a renaissance in jet fighter design in the 70s, producing the F-14 and F-15 long-range air superiority fighters, and the smaller F-16 and F/A-18 multirole fighters. Maneuverability, a wide range of weapons from guns to long-range missiles, and high pilot situational awareness by reducing workload and integrating flight and fire control systems, were all emphasized strongly.
The Soviets were taken somewhat by surprise at this surge; as of when the F-16 first flew, the Soviet air force and those of its allies had nothing that could compete. They answered a few years later with the MiG-29, a smaller twin-engine design similar to the larger Su-27 which was in pre-production to answer the F-15. These six fighters - F-14, F-15, F-16, F/A-18, MiG-29 and Su-27 - represented the cutting edge of fighter design as of the collapse of the Soviet Union in 1991.
The new U.S. designs to enter production since, the F-22 Raptor and F-35 Lightning II, are themselves fairly old; the first production F-22 was built in in 1996 and flew in 1997, almost 20 years ago, the result of a design competition with planes flying back in 1990, and the initial RFP originating in the 1980s. The F-35 first flew in 2006, itself derived from the X-35 JSF testbed which first flew in 2000, so that design is between 10 and 15 years old now depending on how you count. Their protracted development times are a direct result of the reduction in pace of the U.S.-Russian arms race since 1991; with no other technologically-advanced military adversary on the horizon, there simply hasn't been the impetus to get these planes out to the front lines (there is some civilian talk of restarting the F-22 production line to bolster Raptor numbers, as the Sukhoi PAK-FA and Chengdu J-20 are very close to production and the F-35 is way behind projections and proving a disappointment so far, but another 100 new Raptors are projected to cost a ludicrous $225 million each due to increased costs of restarting the line and producing them in parallel with the F-35).
The F-35 also had the handicap of being a return to the "one-size-fits-all" design mentality, being intended as a replacement for practically everything besides the Raptor in the U.S. air arsenal, Air Force, Navy and Marines, with an F or A in its designation. That's caused a lot of technological headaches, since any replacement for the Marines' AV-8B Harrier is going to need STOVL capability, and the Navy and Air Force have always had a different though overlapping set of requirements relating to the Navy's basic need to operate aircraft from a ship at sea that's maybe a fifth as long as the USAF's minimum runway length requirements for its airbases. The resulting design is big, heavy, and relies on the most powerful single engine the U.S. has ever put in a fighter, which pushes the boundaries of the stress limits of the materials we use to make jet engines.
Lastly, military spending in the last 10 years or so has been preoccupied with developing and fielding technology to fight a low-tech insurgency; our enemies know they can't beat us in a toe-to-toe fight, so they don't fight that way, instead targeting our multi-million-dollar military hardware with Vietnam-era milsurp RPGs and oil-drum IEDs costing maybe $100 a shot. On this kind of battlefield, stealth air-superiority aircraft are kind of redundant as the enemy doesn't even have radar, much less an air force to exercise superiority over. That's why the F-22 has never seen real combat; the U.S. has enjoyed "air supremacy" by default in its primary combat theaters, as its enemies have never fielded an air force to speak of.

"The first production F-22 was delivered to Nellis AFB, Nevada, in January 2003", according to wikipedia. The first "production" aircraft built was in 1996, but the first flight didn't occur until 1997. So, it's not new, but it hasn't actually been in service that long.

Although 4,500+ F-16s have been produced, how many are still in service? The USAF only flies around 1,200 of them; I'm not sure if exports come close to the remaining 3,300 airframes built.

@DavidRicherby - Data from F-16.net suggests the USAF has taken delivery of about half the total F-16 production, about 2500 aircraft. A large contingent of those are mothballed. The Israelis are the next biggest customer with 382 ordered, 362 in service. The Turks have 278, the Egyptians 240, the RNIAF about 230, and there are about three dozen more countries that have taken delivery of enough for between two and ten squadrons. Even the Iranians ostensibly have about 160 of them, though they're probably rusted scrapheaps by now along with their F-14s.

@egid The YF-22, which was the demonstrator, flew in 1990. The model from 1997 was also only an engineering aircraft. Over all this time, it cost a lot of money already. It was FOC in 2007, that's 17 years! Contrast that with the F-16, which went from prototype to FOC (1973-1980) in seven years. Also don't forget, that the F-22 isn't produced anymore, while the F-16 is still produced.

It fulfills the role it was designed for adequately, a replacement is not needed so why would they stop using it?
The B-52 Stratofortress was introduced in the 1950s and is still in service.
The airframes are older than their flight crews and have undergone extensive refits over the decades, but the basic design is 60 years old.

The F-16, is a fairly cheap fighter to buy and to operate. Despite its age, it is still a very capable fighter if fitted with the right systems. It is not suitable for every theater. It depends on the level of sophistication of the enemies weapons. If they are too modern, it's better to have a different fighter.
Not every country is able to afford more expensive fighters.
I recently read that in a one to one dogfight between an F-16 and the new F-35, the F-16 is still the master.

I agree with that last assessment; the F-35 is hindered by the need to incorporate design features the F-16 was never saddled with. The F-35 has the most powerful single engine we've ever put in a fighter, and it's still considered underpowered for its weight.

@KeithS, it seems to have worse thrust/weight ratio than anything else and it also has quite high wing loading, so its turning ability is probably also worse.

@JanHudec - the F-35 has thrust vectoring, however, which will help significantly on the maneuverability front.

@JonStory, so does Sukhoi-PAK-FA and even some variants of MiG-29 and they have more reasonable wing loading. The problem with relying on thrust vectoring is that it is less efficient, so the F-35 will be loosing more energy.

Nobody was comparing the F35 to PAK-FA though - the point is that the F-35 isn't as disadvantaged vs the F-16 as the wing loading would potentially suggest, at least in an unsustained turn

The F-16 could easily be upgraded to have thurst-vectoring. It's would not even be an expensive upgrade. One of the pilots that flew it in an operational evaluation told me that in his view, it would never become available to prevent  jeopardising the development of next generation fighters

@JonStory, no. The F-35 doesn't have thrust vectoring. Only the F-35B has thrust vectoring but it's for STOVL operations, nothing more.
Besides, thrust vectoring is not sucha good thing on the "energy" front during a dogfight.

Well F-16s are old but will fly till 2045 here's how:
USAF loves those fighter that are fast,agile,advanced and cheap F-16 has all of them but not advanced so USAF is planning a new production line for F-16
Which is known the F-16V
Prototype will be completed in 2016 but F-16 will be even advanced than F-35. Lockheed has given these words
In addition F-16V will be supermanueverable like sukoi and F-22 without thrust vectoring nozzles

That's interesting information. If you can link to sources for some of those statements, that would make for a great answer.

https://www.flightglobal.com/news/articles/singapore-lockheed-martin-announces-f-16v-development-368323/  I found this article talking about LM announcing the F-16V at the Singapore Airshow a few years ago, but it looks like it's focused on avionics and radar upgrades. No mention of supermaneuverability or anything like that. There have been plenty of technology demonstrators based off the F-16 that explored supermaneuverability and the like, but I doubt anyone would seriously look into adding that level of complexity to a production version of the F-16.

The F-16 has a thrust-weight ratio of greater than 1, so it is a great dogfighter, it is cheaper than an F-22 or an F-35, and it is being upgraded with faster computers and better engines. Also, the F-16CJ/DJs are the Wild Weasels right now, and when the A-10s are retired, the F-16s will make a decent CAS replacement.

The X-15 had a thrust to weight ratio greater than 1 as well; nobody'd call that a good dogfighter. The primary determinant of a good dogfighter is high aerodynamic maneuverability, which breaks down into a number of design considerations, of which power-to-weight is only one.

I also disagree with your assessment of the F-16's capabilities in the CAS mission profile of the A-10. The F-16 was intended for "one pass and haul ass" types of ground runs. It's been used for BAI (destroying enemy forces on their way to the front lines), but it's too fast, too light on internal fuel, too delicate and too expensive to hang around plinking random battlefield targets on demand. The A-10 is one of the cheapest, most durable and well-armed jets of the modern era.

Which is why I said decent. And I agree. the TWR is only a small part. My bad. Also, during Desert Storm, F-16s were called in when all the A-10s were out of area. It is true, though, that the F-16 can't function effectively without drop tanks and the help of a tanker. And the A-10 cannot function when there are are AAA sites or SAMS in the area, so the F-16 in it's SEAD role aids it. Good points though, I'l edit my answer.

F-16's did some fine CAS during OIF. @KeithS  think you may misunderstand what weapons and tools are available for CAS.  A-10's gun is unique; the GBU-12's it carries are not.  Smaller bombes with a variety of guidance packages have been available to the Viper for over a decade. You Don't Have To Have a Warthog if you need CAS. (But yeah, they sure are nice to have ...) Harriers and Hornets also fulfil the CAS role.

The answer is more of a question. Why retire a fighter jet that can still outmatch fighter jet's today. The F-16 is a reliable tested aircraft. It's had years of edits made to it to make it the best of the best.


text:
Who is responsible - CFII or the Private Pilot?
Here's the scenario: There is a Private Pilot working on their instrument rating. Alongside with him is their CFII. Let's say it is just a normal VFR flight, and they're getting back to their home airport after a training flight. Now, after the first radio call, ATC instructs them "NXYZ, Squawk 1234 and ident - remain outside (Airport) Class Charlie".
Even though you just need Two-Way Radio Communications to enter Class C, ATC has strictly advised them to remain outside of it.
Now, for some reason, the airplane goes well inside Class C airspace. After a few minutes, ATC gives a call saying "NXYZ, cleared into Class C, enter left base Runway 18. Possible pilot deviation, advise when ready to copy down a phone number"
The question is - since both the Private Pilot and the Instructor are logging the flight time as PIC, who is responsible to answer? And if a deviation is given - who among the two gets it?

I've never worked on an IR.  Why would both be logging PIC?

@casey The authorized instructor can log all time while providing instruction as PIC time as long as they are rated in the aircraft.  It doesn't matter if they are able to act legally as the pilot in command or not.  See 61.51(e)(3).

There is a contradiction in your question.
You say both the student and instructor are logging PIC.  This is fine, but the authority for this to happen depends on certain things.

The instrument student logs PIC under 61.51(e)(1)(i)

(1) A sport, recreational, private, commercial, or airline transport pilot may log pilot in command flight time for flights-
(i) When the pilot is the sole manipulator of the controls of an aircraft for which the pilot is rated, or has sport pilot privileges for that category and class of aircraft, if the aircraft class rating is appropriate;

They are acting as PIC as the sole manipulator of the controls and must be rated for the aircraft.
The instructor logs PIC under 61.51(e)(3)

(3) A certificated flight instructor may log pilot in command flight time for all flight time while serving as the authorized instructor in an operation if the instructor is rated to act as pilot in command of that aircraft.

This only applies on instructional flights, where the instructor is providing instruction and is rated to act as PIC (e.g. if the instructor lacks a medical and could not act as PIC, they could still provide instruction if the student is the PIC, but the instructor would not be able to log PIC).

The reason I say this is a contradiction is that you claim

Let's say it is just a normal VFR flight, and they're getting back to their home airport after a training flight.

This makes it sound like it is not a training flight and in that case only one of the pilots could log PIC using the sole manipulator rule in the absence of instruction taking place.
It turns out the above isn't directly important, as logging != acting PIC, and the acting legal PIC is what matters from an authority and enforcement perspective.  What the above logging issue gets at is hinting at who might be the legal PIC absent the two pilots agreeing who would act as the legal PIC.
In the case instruction is taking place even though the student is logging PIC  the instructor is also logging PIC and is the "ranking" pilot in the flight and may be viewed as the legal PIC.  In the case of a non-training flight (which would be hard to justify if you both logged PIC), then it comes down to the question -- who agreed to act as the legal PIC?  Either of the student or instructor could act as the legal PIC, but on a non-training flight only the one of you actually manipulating the controls could log PIC.  If there was no agreement prior to the flight over who is the legal PIC, the FAA will still probably decide the CFII was the legal PIC or the FAA may decide to go after both of you.  I believe there is precedent for this in enforcement action, but I don't have any cases handy to reference.

What should you do about this?  Both the student and the instructor should fill out a NASA ASRS form and preserve evidence that you submitted it within 10 days of the event.  If the deviation was not willful and the controller decides to pursue action, this will protect you from enforcement.

Short version: It doesn't matter who is logging PIC time, what matters is who the actual PIC was, as there can be only one.

Oh, and one other point. Many times it doesn't even matter who the PIC was, as the FAA will go after both certificated pilots since they both should have known better.

I'd say that the NASA ASRS report can protect you from enforcement. It doesn't always so saying that it will protect you from enforcement may be misleading.

It's interesting to read all those laws about logging the PIC time. That's because throughout my IR training, my instructor and I would put the entire flight as PIC for both of us. However, I think you're right when you say that what matters is that at the time of the error, the person who was in command of the airplane would probably face the legal problems.

I would think that the instructor will face problems while the private pilot student will not. All the detail about logging is probably extraneous. Based on the second hand stories I've heard the instructor will be held responsible. That said, the FAA can do whatever it wants.

This only applies on instructional flights, where the instructor is providing instruction and is rated to act as PIC (e.g. if the instructor lacks a medical and could not act as PIC, they could still provide instruction if the student is the PIC, but the instructor would not be able to log PIC is not correct.  Read the regulation again, it stipulates the CFI is rated (category, class, type) on pilot and instructor certificate.  They can still log PIC because they are an instructor on a training flight.  I vote to update the answer.

This really depends on whether or not the authorized instructor and / or the pilot can legally be the pilot in command.  By this I mean they are current with a flight review.  Neither the student pilot nor the flight instructor need to be landing current as the purpose of the flight is a training flight.  See the Kortokrax interpretation from the FAA.
If both the student pilot and the instructor is capable of acting as the pilot in command it should be discussed before hand who will be acting as the pilot in command before the flight.  I know of some instructors who keep a binder in their car stating who is the acting pilot in command if an incident or accident occurs.
In you situation, without the pilots discussing beforehand, I would imagine the FAA would hold the instructor accountable.  They have more experience and should of prevented the incursion.  I have heard the FAA holding the instructor or another more experienced pilot accountable even though it was expressly documented the other pilot was acting as the legal pilot in command.  In their view, the more experienced pilot should have said / done something to prevent what happened.


text:
How is a wing joined to the fuselage?
I've seen this video from Airbus:

This is a capture from that video:

What is the process for attaching the wings to the fuselage?

You marked in the comments that you are interested in the process of attaching. Therefore I'd like to provide you some more information. I have done some sketches numbered I) to III) for the Wing Root and another sketch for the horizontal stabilizer installation.
1. Wing Root Joint:
Generally, there are many ways to connect a wing to the fuselage. The most common ones in large commercial aircraft or military jets are:
I) Spliced Shear Plates
This is exactly what you can see in the video. You will find these joints in many large civil aircraft because they are lightweight and inherently fail-safe (because it is a continuous joint, a single fastener failure is not catastrophic). However, they are a bit more complicated in manufacturing leading to higher costs. Furthermore, it might be not feasible for very thin wings (e.g. wings of super-sonic aircraft).

Sketch I) shows a section cut along the so-called cruciform fitting which you see in the video. The wing starts left of the root rib, the fuselage (and center wing box) is right of it. The bolts are placed continuously along the joint and they are loaded in shear. Shear loading is generally a good way of loading for the fasteners, leading to a lighter design.
How is it manufactured? Normally the Fuselage and the Center Wing Box are already build together and the wing arrives separately. In the assembly line, the wing will be moved close to the fuselage so that the wing skin is directly underneath the cruciform fitting. However, it is important to place the wing in the right place. Then you start drilling the holes and connect the wing to the fuselage. There is a German TV show for kids that also shows scientific stuff. Once they provided a full documentary of the assembly of an A321 (Sendung mit der Maus - Flugzeugbau). You might watch this brilliant video to get a good understanding of how the wing is assembled to the fuselage (even worth it if you do not understand a single word of German):
Now you will be able to see what I mean by more complicated manufacturing and why it is complicated to use this concept for very thin wings.

II) Tension Bolts:

I tried to show it in sketch II). You see that both - wing (a) to (b) and fuselage (c) to (d) - have so called tension bolt fittings. Those are relatively strong fittings designed to transfer the wing bending moment in the form of tension loads over big bolts from the wing to the fuselage. You will also have multiple or continuous tension bolts along the joint. You can also see that this assembly is better suited for thin wings and therefore is used for many fighter aircraft or the Concorde. As stated above, it is better to load the bolts in shear... but here you load them with tension loads. This makes not only the bolts, but also the surrounding structure heavier.
III) Lug Fittings:

You have several fittings with lugs on the wing and the fuselage that are connected with bolts. Normally these lugs are located at the wing spars. Having only few lugs and special areas means that all your load path is concentrated towards these points. This leads to heavy reinforcements around the lugs. Furthermore you need to implement additional design features to make them fail safe.
However it is "easy" (compared to the other concepts) to attach them to the fuselage and to take them off again. Therefore you might find them in aircraft that you need to transport (military fighter jets, drones, gliders, ...).
2. Horizontal Stabilizer:
The sketch below shows the fuselage with the dedicated cut-out and the horizontal stabilizer itself. Normally the stabilizer is inserted into the cut-out while the fuselage fittings 1) and 2) are removed. Once the stabilizer is in position, its fittings 4) will be connected to the fuselage fitting / pivot 2) which is put in place again. Then the fittings 3) of the stabilizer will be attached to the fitting 1) of the fuselage. This fitting 1) is sitting on a huge jack screw, so that it can move up and down, while the rear hinge line stays in place resulting in an up and down movement of the horizontal stabilizer. Once everything is assembled, the fuselage rear cone is installed at the end of the fuselage.    (you might also watch more of this German TV show for kids, they have also an internal view of the moving jack screw :-)  )

I hope that answers your question :-)

On lighter aircraft, the wings are sometimes designed to be detachable for ease of transport:

To achieve this, the wing spar has a stump at the inboard edge that is inserted into a hole in the either the fuselage or the next inner wing section.
Once inserted, they are locked to the fuselage (and often to the wing on the other side) using large metal pins. You will also often see pins at the leading and trailing edges, which are there to counter the aerodynamic torque on the wing: due to the way physics work, it is easier to counter torque with a small pin at a distance from the main spar than make the spar large enough to carry it by itself.

Great picture of the airfoil too.

The pins at le leading edge and flap spar also carry the lift forces across the joint. The spar only transfers the bending moment.

@PeterKämpf You mean they transfer shear? Otherwise I don't think I follow. In my experience with a similar design the spar was sized to carry both bending and shear, but that was one solution, it might be different on the glider in the pictures.

Yes, and shear only. After all, they are just sticking in corresponding bushings, without any locking mechanism except that provided by the spar bolt. This is a standard design used in all German composite gliders.

@PeterKämpf do the LE and TE pins go all the way along the span then? The design in the images does look a bit odd to me; for one I expected the spar to be further forward (near the quarter chord), but your comment does shed some light.

@AEhere: The spar is where the airfoil has its maximum thickness. That is at about 40%. I don't quite understand what you mean by going "all the way along the span" – the shear pins transfer load between the ribs of a joint. So they are where the glassfiber structure is interrupted. To be honest, some lift force is also transferred via the spar bolt – how the forces are distributed is determined by local stiffness. But when dimensioning the shear pins you add the loads from torsion and from lift.

@AEhere: And by "shear pin" I don't want to imply that they have a load limiting function – they are actually quite oversized. The name implies that they are loaded in shear. In German their name is "Querkraftbolzen".

I’m a retired FAA licensed A&P mechanic. The wings on the B727 are held on, in part by so called “bottle pins” if memories serves there are two on each wing roughly the dimensions of old fashioned glass quart milk bottles. I’m only “assuming” there are similarities to how the B737max wings are also held in place. Again I’m assuming that the “pickle fork” structures are an adjunct to another center box fitting such as the B727 bottle pins. Any more current info would be interesting.


text:
What is this on the aft end of this GEnx engine?
In the next picture, corresponding to a GEnx engine, what is the item circled in red?

Thank you very much again.

The pipe is the center vent tube which vents air from the oil sump.
From airliners.net (User MD11Engineer):

All gas turbine engines use pressurized seals for their shaft bearing compartments to keep the oil in. The result is that the scavenge oil returning to the oil tank via the scavenge pump, chip detectors and scavenge filter contains a lot of air, it is more a foam than a liquid.
Engines use a centrifugal oil / air separator in the circuit to remove the air from the oil and to vent the system to the ambient to avoid overpressure.
PW and RR use centrifuges attached to their main gear box, which vent overboard through a hole in the cowling.
GE and CFM use the hollow N1 shaft as a centrifuge. The heavier oil sticks to the inside of the shaft and gets returned into the circuit via holes, while the lighter air stays in the center and gets blown out through the pipe in the back.
The air blown out is not completely free of oil, so when the engine has just been shut down, you´ll see some oil vapor coming out from this pipe.

Source: www.airliners.net
Similar vent is found in other GE engines, like the GE90.

Source: airwaysnews.com
The system looks like this:

Source: CFM56-3 Training Manual, thanks to mins.
This is the actual part in GE90-100:

Source:standardaerocomponents.com

CFM56-3 Training manual, multiple diagrams with the vent tube and the oil scavenge system (search vent or oil in the document). Example.

@mins This is a much better diagram, if you ask me. If its OK with you, I'll add it to the answer (with proper credits, of course)

authors: Вадим Войтенко


text:
Is there any plan to make flights more interactive using smartphones?
This question might be a little bit off-topic, but I'll give a try.
Me and many people are aeronautics "aficionados" that would love to know about flying data during flight. Today we all have smartphones that run apps for everything: why couldn't airplanes have an internal WIFI for only broadcasting flight data for being displayed in our smartphones (i.e. as if they were cockpit simulators) as well as video streaming from external cameras? Of course this kind of internal network's purpose would be to broadcast data, so security wouldn't be an issue.
Does anybody know if aircraft manufacturers plan to develop such kind of project?

Actually some airline did it already.
Many Airways including Qantas, Virgin American, Delta, Lufthansa and DragonAir (but Cathay not) has installed Wireless inflight entertainment system which allows passengers to access entertainment system and track flight via their mobile/tablet.
Surprisingly some LCC like Virgin Australia and Southwest also provides wireless on-flight entertainment system, though some contents is not free of charge.
On the other hand, several airline use Tablet to replace the original inflight entertainment system in upper class like La Compagnie (All business class airline), as well as some paid onboard entertainment services in LCC.

Also on Southwest, you can view a flight tracker through WiFi for no charge.

Many airlines have done this already.  It's much cheaper for the airline to provide a wifi network within the airplane that passenger devices can use than to run a screen and the corresponding hardware to each seat.  The screens and all the cabling required to make them work have a significant cost in weight, space, maintenance, and complexity -- all things which airlines hate because it costs them money.  A wifi access point capable enough to stream video to a couple hundred devices and a small server with enough storage to store music and TV programs and movies can probably be done with less than 20 kilos of additional weight, so this is a big gain for the airlines.
When you combine that with either a satellite or a terrestrial receiver for internet type data, you have a relatively complete system for people to use smartphones, tablets, computers, etc.
How much the airlines charge for this, or whether they offer some of the services for free becomes more of a business / pricing decision than a technical one.  For any local (meaning "stored on the airplane") content, the onboard wifi is more than enough bandwidth for the users.  For anything that has to communicate via the satellite or terrestrial data link, the cost to the airline will almost always be high enough that they will want to pass those costs on to the passengers.
As of this writing (Sept 2015) I've been on a number of United Airlines flights where the local cached content (streaming movies and TV shows) are free for people to use, and you can also get to a selected set of webpages which are locally generated and show things like the aircraft location, the ground speed, the estimated time of arrival, etc.


text:
How common is it for military jets to use civilian airports?
Today my wife witnessed 3 fighter jets taking off from Teterboro Airport in NJ. She even took a video. How common is it for military jets to use civilian airports?

When they're relocating from base to base, they gotta fuel up somewhere.   Many larger FBOs have contracts to provide fuel and basic services to the military.

Fighter jets may fly into local fields for airshows, to re-fuel or for needed maintenance in route etc.
What your wife may have seen may have been related to the VIP TFR's that usually pop up in the summer due to the president (or first family) heading back to their home on weekends.
I fly out of KDYL which is fairly close (in aviation terms) and my local FBO has been warning everyone that the Secret Service has instructed them the VIP TFR is going to be common on weekends this summer.
You can find a map of current TFR's here.

Some airports are shared with the military. For example, Portland International in Oregon has the Portland Air National Guard Base, and Charleston International is shared with Joint Base Charleston. Airports such as these will have frequent military traffic.
Even airports with no permanent military presence may see occasional military traffic. Aircraft may do touch-and-gos there for training. It's less likely for them to stay very long, as there could be special security and ground support requirements, especially with fighter jets.
You can look at statistics for US airports on AirNav. KPDX sees military operations as 2% of its operations, while KCHS sees 20%. KTEB shows <1% of its operations are military. This is the lowest value they report but that could still be up to almost 5 per day on average.

A decade or so ago, when I kept the Cherokee at Reno (the FBO on the east side of the field), it was quite usual to have something military - from F-14s to C5s - parked on the ramp.  There's also an Air National Guard base on the east side, flying C-130s last I looked.

Non-US example https://www.google.pl/maps/place/Krak%C3%B3w+Airport+im.+Jana+Paw%C5%82a+II/@50.0749105,19.7849321,1504m/data=!3m1!1e3!4m5!3m4!1s0x4716592789d2e8d1:0x93efc553923da128!8m2!3d50.0769776!4d19.7881188 - international terminal is on the right, while military part is in the center.

There are many, many Air National Guard Bases at Regional and Municipal airports. The ANGB planes typically have their own ramp area and hangars for repair, and have security systems around them.
Wikipedia has a list of ANGB locations
Those Not at an Air Force Base are generally sharing civil airports.

Night and day, seven days per week at KABI. This full time-use of a regional airport began early 2018.
Remember the song, "Abilene - Abilene... prettiest town I've ever seen..."  They should make a new song, "Loudest town I've ever seen..."


text:
What is the purpose of proximity sensors on hydraulic systems?
One of the planes I worked on had ground spoiler response checked with proximity sensors. The reason mentioned for that was - "The ground spoiler is hydraulic only - hence its response will be checked with proximity sensors"
Landing gear control unit reads the proximity sensors and flight control system receives the signals indicating deployment of ground spoilers by landing gear control unit.
What are proximity sensors?
Why are they used because the surface is hydraulic?

A proximity sensor is any sensor that detects whether there is something in its proximity (within specified distance).
There are many kinds of proximity sensors (optical, magnetic, capacitive etc.) that detect different kinds of target objects and to various distances.
In this case, proximity sensor is used to detect position of the spoiler. Proximity sensors are preferred over micro-switches because they are more reliable, since they have no moving parts and thus don't wear out.
For parts actuated with hydraulics they are the only way to detect the position, since hydraulic actuators don't provide any direct way for detecting their position (compared to electric actuators, where in some cases the response of the actuator can be used to detect the position; the principle is similar to a magnetic proximity sensor anyway though).

Likely magnetic? Why? Aluminium isn't magnetic, and would be easier to detect with capacitive sensor.

@MSalters, it can be magnetic, if it is detecting something iron (in the actuator itself), or eddy-current (which uses electromagnet) or capacitive if detecting something aluminium.


text:
Is there any data repository of discontinued commercial routes?
Is there any way of knowing - for example by referring to an existing data repository or something similar - what commercial routes were operated from a given airport in a given year?
This would be a list of all commercial routes that have been discontinued.

Do you mean flight plan routes, or service between airports?

Services between airports

departedflights.com has a list of historical routes both by airlines and (a few) hubs. Though it is not complete, it has a lot of data.


text:
Who flies planes on ferry flights?
Two questions regarding ferry flights:

When an aircraft has to be delivered, who flies it to the destination airport? Does the manufacturer have a dedicated crew for this or is it up to the airline to send someone over?
When an aircraft is sent to Victorville (Southern California Logistics Airport), who flies the plane? Is it a dedicated airline crew or is it a contracted-out service?

Thanks!

When I just saw the title question, my first thought was "Pilots, usually."

Not really an answer, but there was a recent BBC article about this very subject http://www.bbc.co.uk/news/magazine-34484972

@reirab "Usually"?!?!?  Okay, um... who flies them in the, well, "unusual" ferry flights?  :-)

Ferry flights encompass much more than delivery and retirement flights.  Any time an airplane has a problem that can't be fixed on-site they can generally obtain a ferry permit to get it to an airport that the maintenance can be completed at.
At the airline I worked for, all flights, including initial delivery, were conducted by pilots on our seniority list and other airlines I'm familiar with have the same requirements in their contract language.  Our airplanes were manufactured in Brazil and a crew would be take an airline flight down to the Embraer factory, accept the airplane and fly it to a US customs station and then on to our main maintenance airport.  These flights were fairly uncommon and often went to very senior and management pilots.
Normal ferry flights for aircraft repositioning or maintenance needs were generally done by low-seniority reserve crews because those tended to be non-scheduled activity and show up with short notice.
In all cases though, at my airline, ferry flights were conducted by company pilots.  This can vary by airline and there probably isn't a universal definitive procedure common to every airline.

Usually, ferry and delivery flights have different meanings. It differs from aircraft to aircraft.

In case of new commercial aircraft, the delivery team from the airlines are sent to the manufacturer, where they accept and bring the aircraft to the airline location. The delivery procedure of Airbus is as follows:

The delivery phase is spread over four or five days on average, dependent upon the aircraft programme. A standard delivery procedure takes place as follows:
1st day: ground checks: external surfaces, bays and cabin visual inspection, static aircraft system and cockpit checks, engine tests.
2nd day: acceptance flight: checks during flight of all aircraft systems (including cabin systems) and aircraft behavior in the whole flight envelope.
3rd day: physical rework or provision of solutions for all technical and quality snags open in delivery.
4th day: completion of technical acceptance. Technical closure of the aircraft and all associated documents attesting the aircraft’s compliance to the type certificate and conformity to the technical specification allowing the issuance of the Certificate of Airworthiness.
5th day: transfer of the aircraft's title deeds to the customer airline: the aircraft changes owner. Preparation of the aircraft for the ferry flight to its home base.

For GA, ferrying is done by ferry pilots. There are also some companies that perform these services for small airlines etc.

A ferry flight usually refers to the positioning of aircraft for maintenance, repair etc. This is done by the pilots of the airlines usually, with a special permit (i.e. the aircraft is not airworthy, but is flyable). As noted before, this can also be contracted out.

For military aircraft, it is done by the service pilots.

Could you clarify what you mean by "service pilots"? Are those pilots trained for non-combat operation only?

@Lilienthal: I know that a lot of European F-16's were flown from the States, which necessarily involved mid-air refueling. That is a skill rare outside military pilots, and the various Air Forces are not going to train a set of non-combat pilots just for these one-off ferry flights.

@MSalters Hmm, maybe. I kind of imagine pilots starting out without a combat certification and then following more advanced training and thousands of sim hours before being allowed into combat. Plus, regular ferry flights probably won't be trans-atlantic.

@MSalters: I don't know that crossing the Atlantic with an F-16 "necessarily" involves mid-air refueling.  Wikipedia quotes the ferry range of the F-16 as 2280 nmi (with drop tanks).  If you're willing to make some stops, that's no problem.  JFK-YQX-KEF-LHR has its longest segment at 1371 nmi.  Throw in a stop at GOH in Greenland and you get it down to 922 nmi - probably don't even need the drop tanks then.

@Lilienthal: Given MSalter's point, I think aeroalias means "service" as in "armed service", not as in "maintenance/repair".  i.e. a US air force pilot would fly a US air force plane if it needed to be ferried anywhere.

@NateEldredge: I think you're right. Some googling showed that the Belgians and Dutch fairly regularly cross the Atlantic for Red Flag, but the Belgians use drop tanks and the Dutch use in-flight refueling. Makes sense, as only the Dutch have the KC-10 tanker.

@MSalters Dutch also used to refuel at NATO base Keflavik (Iceland) instead of using tanker. (At least until 2008 when a friend of mine was sometimes flying those F16's to the States.) Don't know about the situation since then.

All the new aircraft deliveries I have been involved with were done by the buyer or the leasee. The normal process involves a physical inspection of the aircraft, paperwork, accessories, making sure the correct documentation is in hand, as well as one or more test flights to assure aircraft performance.  In every delivery I have accepted, there is usually a squawk list, and the manufacturers are great at performing seeming miracles overnight.  It is not uncommon that there is a couple of days of squawks. I often invite a factory test pilot along on the flights, as that helps identifying issues.
Some of the things I check include the rigging and trim of the aircraft, the power plant performance, the radio installations (which can require some coordination when picking up a plane mid-continent and testing HF), the autopilot systems, and the ECS.
Funds are transferred and paperwork is filed, and a flight to the destination is accomplished. Normally close fuel and power plant monitoring is done for that flight, and things like WX radar, strike finders and other avionics are extensively run.
If we don't have someone who has significant experience in the aircraft, we take training at a place like Flight Safety, in a simulator. Training is normally classified as initial or recurrent.  The training outfit can tailor the training to include the specific equipment and engines that are included in the delivered aircraft.
The bulk of the aircraft I have personally accepted of delivery on are turboprops and jets, but it also includes a few piston aircraft. Some local flight schools, charter and FBOs have hired me to accept delivery of aircraft for them.
In my opinion the acceptance of new aircraft is more than just kick the tires and ferry the aircraft.  It is a through systems checkout, and verification that all documentation is in place, cosmetics are good, and so, verifying that the end user receives a plane which is unlikely to have any issues, and that it performs as advertised.


text:
Does ATC handle non-regular widebody flights differently?
Six weeks ago, roughly, a Corsair charter flight landed at Lamezia Terme International Airport (SUF), in Southern Italy. It was a Boeing 747-422, registration F-HSEA. It carried 500 tourists from Liege Airport (LGG), Belgium.
My question: when a flight like this is headed to an airport which is not an usual landing spot for wide-bodies, how does the ATC figure out a wide-body is coming? Do they figure this out by just communicating with the pilots when airborne or do they receive an official note beforehand?

Well, doesn't the ATC receive the flight plan ?

The flight would've filed a flight plan which has data about the aircraft type.

If ATC didn't handle this flight, who would?

No, ATC does not handle these flights differently from regularly scheduled ops
ATC isn't concerned with why an airplane wants to go to an airport or whether they regularly operate there or even if there are ground services available for them at the destination.
Whether the flight is regularly scheduled or not may fall under different regulations but ATC services do not vary.  The charter flight will be operated under instrument flight rules (IFR) and will have a flight plan filed with ATC prior to departure.  The controllers at the departure airport will receive information about the flight prior to that planes departure and will service the flight to its filed destination.  This works exactly the same way as normal scheduled service by that same (or any other) airline.

To add to this: If by any chance some airplane is flying under VFR without any flight and they want to enter an airport (let's say, as a diversion because they couldn't land at their destination), the ATC/Approach controller can easily ask "(callsign), say type aircraft".

Flight plan aside (if you are going VFR) here in the US you identify your make/type when hailing the tower. For example  if you enter the Delta Airspace around an airport your hail may be

Northeast tower; Piper N347G4 At 3000 with information Mike requesting clearance to land.

In this case the tower will know you are a piper and may (if available) assign you to a smaller runway if they have say two parallel runways of differing lengths or ask if Land And Hold Short is possible for you. I have even had the tower ask what type I was ("Arrow", "Cherokee", "Warrior" etc.). This will allow the tower to sequence traffic with any special needs as may be required. If a large jumbo is coming in followed by a small Cherokee 140 they may have the Cherokee extend its downwind to help avoid wake turbulence (they will also warn the Cherokee of possible wake turbulence).

Just to add to this: Small airports under Delta airspace usually don't have radar service, and hence they "look" for you using binoculars and advise you if you're not in their sight.
Just the other day, it was marginal VFR conditions and I was told by the tower of a Delta Airspace that "Nxyz, not in sight, cleared to land RW 04, number two - behind the Citation on a 2 mile final, report traffic in sight"

On the other end of the scale, heavy (most airliners are heavy) and super (A380 and An225) aircraft add the HEAVY and SUPER to their callsign so that the controller (and any other pilot on the frequency) are reminded of the required separation for wake avoidance.